Foster has never revealed her handsome sons’ paternity and has reportedly said she won’t tell the boys until they turn 21.

“The kids look like him [Gibson] but blonder,” said one amateur genealogist.

If Gibson, a father of eight, donated his sperm to Foster, it would explain her fierce loyalty to the troubled star while the rest of Hollywood shunned him over his anti-Semitic remarks and abusive treatment of Oksana Grigorieva, the Russian girlfriend who bore his last child, Lucia, 3.